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    <script>
        //邮箱以这些结束.com|.cn|.sina|.net

        //1.以5-12位数字或者字母（大小写都可）开头，+ @
        //2.(163|126|qq)选择其中一个；
        //3.(sina|cn|com|net)以其中一个结尾。
        var reg = /^[0-9a-zA-Z]{5,12}@(163|126|qq)\.(sina|cn|com|net)$/;
        var str = '1427076399@qq.com';
        console.log(reg.test(str));
        
    </script>
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